Georges Simenon (1903-?) wrote over 400 novels, 200 as Simonen and the
rest under twenty-three pennames.

John Creasey (1908-1973) published 565 books (some say more), under
his own name and twenty-five pennames.

Anyone who has taken any writing workshops or attended any writers'
conference, has no doubt heard over and over again, "If you want to be
a writer--write." You have to produce the words to get a finished product.

Comments on Production

"Nine out of ten writers, I am sure, could write more. I think they
should and, if they did, they would find their work improving even beyond
their own, their agent's, and their editor's highest hopes."

- John Creasey

"Talent is a matter of quantity; talent doesn't write one page, it writes
three hundred."

- Jules Renard

"Thinking is the activity I love best, and writing to me is simply thinking
through my fingers. I can write up to 18 hours a day. Typing 90 words a
minute, I've done better than 50 pages a day. Nothing interferes with my
concentration. You could put on an orgy in my office and I wouldn't look
up - well, maybe once."

- Isaac Asimov

Just What Counts as "Writing Time?"

It's natural to look at words or pages in-hand to assess writing production.
However, feeding the mind of the muse is also part of the writing effort.
Research time-- revision time--proofreading time--thinking time--are as
much a part of writing as is time spent tapping fingers on the keyboard.

Dylan Thomas was once asked if he had done any work that day. He replied,
"Yes. I spent the morning putting in a period--and the afternoon taking
it out."